Asphalt-surfaced roadways are built to facilitate vehicular travel. Depending upon usage density, base conditions, temperature variation, moisture levels, and/or physical age, the surfaces of the roadways eventually become misshapen and unable to support wheel loads. In order to rehabilitate the roadways for continued vehicular use, spent asphalt is removed in preparation for resurfacing.
Cold planers, sometimes also called road mills or scarifiers, are used to break up and remove layers of an asphalt roadway. A cold planer typically includes a frame propelled by tracked or wheeled drive units. The frame supports an engine, an operator's station, a milling drum, and conveyors. The milling drum, fitted with cutting tools, is rotated through a suitable interface with the engine to break up the surface of the roadway. The broken up roadway material is deposited by the milling drum onto the conveyors, which transfer the broken up material into haul trucks for removal from the worksite. As haul trucks are filled, they are replaced with empty haul trucks. The filled trucks transport the broken up material to a different location to be reused as aggregate in new asphalt or otherwise recycled. This transport process repeats until the milling process is finished.
To remove a layer of asphalt from the roadway, the cold planer travels forward at a generally constant speed while the milling drum is in a lowered position and rotating. As the cold planer travels forward, the haul truck must also travel forward in order to continually receive the broken up material ejected from the conveyor of the cold planer. To avoid situations where material spillage can occur, such as when the haul truck is too far from or too close to the cold planer, operators have implemented signaling techniques that allow cold planer operators to communicate to haul truck operators when to speed up or slow down during a milling operation. Known signaling techniques typically require the cold planer operator to continually monitor the distance between the cold planer and the haul truck and manually send positioning signals to the haul truck operator, such as with the blast of a horn. However, these techniques can distract the cold planer operator from other important aspects of operating the cold planer and involve the operator's subjective interpretation of proper distancing between the cold planer and haul truck. Further, the manual signals can be difficult for truck operators to interpret at times, resulting in miscalculated control and material spillage.
One attempt to provide automated position signaling to a haul truck during a milling operation is disclosed in U.S. Patent Application Publication No. 2013/0076101 A1 of Simon that published on Mar. 28, 2013 (“the '101 publication”). In particular, the '101 publication discloses a system for automatically determining a distance between a milling machine and haul truck and simultaneously triggering control commands to the operator of the haul truck. The system includes a milling machine equipped with an ultrasonic sensor attached to the front of the milling machine for determining the distance between the milling machine and a haul truck. A controller connected to the sensor determines when the haul truck reaches a minimum or maximum allowable distance from the milling machine and generates “forward” and “stop” signals to command the haul truck operator to move forward or stop moving when the minimum or maximum distance is reached, respectively. This stop-and-go process continues until the haul truck is filled.
While the system of the '101 publication may allow for automated command signal generation to the haul truck operator, it may not be optimum. In particular, the “forward” and “stop” commands generated by the system of the '101 publication may cause the haul truck operator to react too quickly, too slowly, or in a jerky manner to the command signals. Further, the system of the '101 publication may deprive cold planer and haul truck operators of the ability to control material distribution within the haul truck and may limit them to the use of stop-and-go filling techniques.
The truck position control system of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.